The invention relates to a method for controlling the feed of a pressure-fluid-operated rock drilling apparatus when a rock drill is fed forward by a pressure-fluid-operated feed motor.
The invention further relates to an arrangement for controlling the feed of a pressure-fluid-operated rock drilling apparatus comprising a rock drill, a feed beam along which the rock drill moves, a pressure-fluid-operated feed motor for moving the rock drill along the feed beam, control means for adjusting the feed of the rock drill, and means for adjusting the flow of the pressure fluid and thereby the feed rate of the feed motor.
The aim in rock drilling is on the one hand to control the entire drilling operation such that ineffective time can be minimized and on the other hand to conduct the actual drilling operation such that a hole can be drilled as close to the desired position as possible, while the apparatus is subjected to as little wear and damage as possible. In practice, the impact and rotation parameters and the feed of the rock drill in today's rock drilling apparatus can be adjusted by different controls. In practice, solutions widely used are the ones in which the drilling power is adjusted and an automatic control adjusts both impact and feed pressure in accordance with pre-set control parameters. Because the rock to be drilled and the drilling situations vary, there usually also exists a separate manual feed control system by which the feed pressure can be deflected from the pressure defined by the parameters, so that the drilling operation can also be adjusted in accordance with the conditions. In connection with collaring, or before the actual drilling is started, it is, however, difficult to adjust the drilling operation by adjusting the pressure of the feed, since the feed pressure does not take into account, for example, the effect of an inclined surface on the motion of the drill bit and on the bending of the drill rod, and the drilling step is therefore not very easy to adjust at present. The position of the feed apparatus and various friction factors in the feed apparatus as such make it impossible to accurately control the collaring step and the moving of the drill bit to the rock surface with one and the same pressure value.